Jesus' private conversation with Peter in John 21 was a set-up. It's an odd conversation. Three times, Jesus asks Peter, "Do you love Me?" Why? I think it's because Peter denied Him three times, and Jesus is giving him the chance to affirm Him three times.
But the words they use are interesting. When Jesus asks the question the first time, He uses the Greek word agape. He's saying, "Do you love Me with a divine, fervent, intense, unswerving love?" And Peter responds with the Greek verb phileo, which means "I admire you as a close friend." The second time, Jesus again says agape, and again Peter, knowing his own failures, says phileo.
The third time, Jesus goes down to Peter's level and says phileo. Peter gets the hint. Jesus knows him better than he knows himself. Peter isn't the rock he thought he was. "Lord you know all things, you know that I phileo you."
You might think that's very cruel, but no, it's very gracious. Jesus is saying, "We both know who you really are, but I'm giving you a commission anyway: Feed my sheep. It's not over, Peter. Even with that kind of love, just the admiration, I can take your life, and I can use you."
If you think that you have to be perfect before God will use you, let Peter's life be an inspiration to you. Forget all the old paintings with Peter wearing a halo. This is the guy who denied Christ, and finally had to admit "My love isn't that agape kind. I just admire you. I can't say that I can love you to the death." And Jesus tells him, "It's all right, Peter. Feed my sheep."
Did Peter ever graduate to the agape level? Yes. Read his epistles. He used the word over and over again. And history tells us that Peter was crucified upside down--because he said he was not worthy to die in the same manner as his Lord.
Do you want to see the Holy Spirit work through your life? Avail yourself to Him. Let Jesus breathe His Spirit into your life. Become commissioned. Try it. Speak up. Quit hiding behind those excuses--away with them! Yes, it's true; not everyone is given the gift of an evangelist or a pastor-teacher. But you'll be surprised at what God can do with a willing person. He can do great things through your life.
I always say that if God can use me, there's hope. Look at 1 Corinthians 1:26-29. "God has chosen the foolish things of the world to put to shame the wise" (v. 27). God will often pass over those who seem to be so wise, and instead use the ordinary people, so "that no flesh could glory in His presence" (v. 29).
When God does a fabulous work through a simple vessel, people should look at the work and glorify the God who did the work! That's why if you say "I'm so inadequate," I say, "You're perfect, you're just right!" To be used by God, be directed by God and infused by His Holy Spirit. He wants to use you!